1. Field of the Invention
The present invention relates generally to a suspension harness-body jacket arrangement which is adapted for suspending all or part of a person's weight relative to a rigid support frame. It is useful in a variety of medical applications, for example, for alleviating the conditions which cause pressure sores to develop in persons confined to a wheelchair, for assisting medical personnel in handling and treatment of incapacitated patients, and for aiding incapacitated patients during therapy and recovery.
2. Description of the Prior Art
Nourishment for body tissues, including skin, fat, and muscles, is delivered by blood vessels carrying blood rich in oxygen and nutrients to these tissues. These blood vessels are called arteries, which subdivide into smaller arteries, arterioles and finally capillaries. Exchange takes place at the capillary level with the blood yielding up oxygen and nutrients for the metabolism or nourishment of tissues. Blood vessels which return blood and the waste products of metabolism are called veins. Veins converge into larger veins which convey this blood back to discharge gases and other waste products in a continuous cycle. The pressure on the arterial side of the blood flow averages between 80 and 120 millimeters of mercury.
An average person seated on a hard seat or chair exerts selective pressure on the pelvic buttocks bones, which are known technically as the ischeal tuberosities. Such pressure can reach between 120 and 150 millimeters of mercury. It is a common behavior for a person so seated to shift his or her weight-bearing postural attitude or elect to arise and move about for short periods to relieve such pressure over the bony prominences. The pressure exerted on the bony prominences may variably bear in excess of the arterial pressure, thus tending to deprive the overlying soft tissues of oxygen and nutrients.
The reduction in oxygen and nutrients delivered to the tissues due to excessive pressure activates sensation nerve endings in the affected areas. These nerve endings relay messages to certain areas of consciousness in the brain which are interpreted as discomfort. The sensation of discomfort, depending on the degree and duration of the excessive pressure, tends to cause a shift in the weight-bearing postural attitude, even in sleep, thus preventing devitalisation or damage to the tissues.
Persons who have little or no sensation faculty in certain portions of their bodies due to an injury or the like will not perceive the normal sensory messages of discomfort. As a result, the affected tissues of such persons frequently develop decubitus ulcers or "pressure sores." Pressure sores are a common problem for persons who are confined to a bed or wheelchair, particularly for those suffering from spinal cord injuries. These persons may develop ischeal decubiti (pressure sores on the buttocks) as a result of sitting for a period of time during which excessive pressure bears on the insensitive areas of the buttocks.
One technique for reducing the risk of developing pressure sores is to teach the patient through medical rehabilitation to do frequent pushups while seated in a wheelchair. This is accomplished by placing one's hands on the arms of the wheelchair and pressing downward, thus lifting the torso upward off of the seat. This technique may not be feasible for persons who have difficulty using their arms or are too weak to push themselves up off of the seat.
Another technique for preventing pressure sores the use of cushions or mattresses of varying configurations and materials. These devices operate to more evenly distribute the body weight of a person over the load-bearing surface in order to prevent excessive pressure from being developed. A disadvantage of these devices is that they cannot be easily and quickly adjusted for persons of various weights and sizes.